The invention relates to gas sensing devices, and in particular to apparatus which detect the presence of toxic gas in the air and which emits a signal being linearly proportional to the toxic gas concentration in the surrounding environment to a display device.
Conventional gas detection systems have been designed to utilize electrochemical sensor devices in conjunction with combined processing and display units. The canister-type sensor devices are arranged as separate units and are connected to the processor/display units by hard-wiring or pin and socket connections. The response of the sensor device is transferred to the processing circuitry, and thereafter a display of appropriate information, such as gas concentration, is generated.
The conventional gas detection systems have as drawbacks the manner in which the sensor devices are interchanged or replaced, and the separate configurations of the processing circuitry and the gas sensor device. In order to change the gas sensor units in the conventional systems, the operator is required to either rewire the sensor device to the processing unit or carefully orient the sensor device so that the pins and sockets align with one another for connection. The lack of self containment of the sensor device and the processing circuitry can tend to be cumbersome to the operator of the system.
It is an object of the present invention to provide a self-contained gas detection apparatus in which both the gas sensor device and the processing circuitry are configured in a common housing.
It is another object of the present invention to provide a gas detection apparatus which enhances the ease in which gas sensors units may be replaced or interchanged by eliminating hard-wire and pin and socket connections.